Gasket and gasket tape and method of making and using the same

ABSTRACT

A gasket material for sealing between two members, The gasket material includes a flexible, woven skeletal member. Enclosing the skeletal member is a flexible, compressible resilient body member having a tacky outer surface, the tacky outer surface for engagement between the two members. In a preferred embodiment the flexible skeletal member is closer to a top surface of the resilient body then it is to a bottom surface of the resilient body. The resilient body may be comprised of urethane. The flexible skeletal member may be comprised of a metallic or a non-metallic material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Gasket material, more specifically, a gasket material comprising aresilient, pliable body having a skeletal mesh member embedded therein.

2. Background Information

A gasket is a sealing member for use between two mating surfaces to helpprevent the movement of fluid or gas between the mating surfaces.Gaskets are often used on vehicles such as aircraft to prevent moisturefrom corroding the sealed off areas and the mating surfaces. Forexample, on the outside skin of an aircraft antenna are often mounted toassist in communications between the aircraft and a remote location.Such antennas often consist of a tabular mounting plate having an innerand outer surface, the inner surface mating to the outer skin of theaircraft and having an electrical connector projecting from the innersurface. The electrical connector is intended to fit partially into theinterior of the aircraft through a small opening in the aircraft skindesigned for such purpose. The electrical connector element will connectto the appropriate electrical circuit in the aircraft. On the outersurface of the mounting plate, and often incorporated with the mountingplate, is the antenna transceiving member for transmitting and/orreceiving radio frequencies.

Traditionally, the antenna is removably mounted to the aircraft throughtypical threaded fasteners. Holes in the tabular mounting plate of theantenna support the threaded fasteners which pass into the aircraft'sskin, typically threading into blind nuts mounted against the insidesurface of the aircraft's skin.

Gaskets typically are provided for covering a portion of the “footprint”of the antenna against the outer surface of the aircraft. When thefasteners are tightened down, they compress the gasket typically withsome defamation, between the aircraft's skin and the inner surface orface of the antenna mounting plate. This is done in an effort to preventmoisture from penetrating the gasket barrier.

However, prior art gaskets have a number of shortcomings whichapplicants novel gasket material overcomes. These shortcomings includeallowing moisture to penetrate the area between the antenna and theaircraft's skin. Often, for example, a site of corrosion is the junctionbetween the antenna inner surface and the electrical connective elementsof the antenna. Moisture has been found to “pool” in this area,accelerating corrosion. Further shortcomings of the prior art gasketsinclude their moisture content or moisture absorption ability, whichmoisture may encourage the formation of corrosion, when the gasket isunder pressure between the mating surfaces and, especially, where suchgasket includes a metallic element. Further shortcomings of the priorart gaskets include their “non-selective retentivity.” This means thatafter the gasket has been installed and in use for a period of time,that upon an attempt to separate the antenna from the aircraft's skin,some portions of the gasket will non-selectively stick to portions ofthe aircraft's skin and other portions of the gasket will stick to theantenna (see FIG. 1A.). The result, often, is the destruction of thegasket.

Applicants have invented a gasket with a novel combination of propertiesand qualities that effectively prevent moisture from passing the sealedarea while maintaining selective retentivity. This allows the effectiveseparation between the mating surfaces upon removal of the antenna.

Flexibility, resiliency, compressibility and pliability are otherfavorable properties which help affect a good seal between the matingsurfaces.

All of these beneficial properties should have a useful life that isreasonable in view of operating conditions and aircraft maintenanceschedules. The gasket should be inert, that is non-reactive with thework pieces (typically aluminum) as well as non-reactive to water,including salt water.

Not surprisingly, it has proven to be a challenge to develop a gasketwith these properties that will survive repeated heat and pressurecycling (as the aircraft climbs and descends), structural flexing, andvibration while protecting the aircraft components and having a usefullife.

While some of the prior art gaskets have provided some of the favorableproperties set forth above, none have provided all of these propertiesin an aircraft gasket with a useful life. Such typical useful life wouldbe a minimum of greater than one year under proper torquespecifications.

Applicants, however, provide for all of the above properties in anaircraft gasket and gasket tape and a novel method of manufacturing theaircraft gasket and gasket tape. Gasket tape is gasket material that isrolled into tape rather than precut to the pattern of the matingsurfaces. Applicants further provide for a method of using the preformedgasket with a liquid setable gel too, in some cases, help insure awaterproof seal.

Applicants have also found a novel method of preparing a gasketmaterial.

Applicants provide a gasket with the following beneficial properties,heretofore unavailable in a preformed gasket or a gasket tape:elasticity (with memory), low water absorption, low water content, leakfree (especially of silicon oil), dessication resistant, compressibilityand surface tackiness (including selective retentivity).

The elasticity and pliability helps make an effective seal between thetwo mating surface as compression against such elasticity helps sealover mating surface irregularities and structural flexing or vibrationof the two surfaces. The maintenance of this elasticity property isimportant since the surfaces undergo thermal expansion and contractionduring repeated altitude and temperature changes which causes relativemovement (flexing) between the mating surfaces.

Low water absorption and low water content is also a beneficial qualityas it is typically water or moisture that the gasket is meant to keepout.

Nor should a gasket material itself be the source of oil, as such oilcan mar the finish of the aircraft surface. This oil leaching has been aproblem with prior art gaskets including those silicon-based gaskets.

An additional beneficial property of an effective gasket includes aresistence to drying out. Drying out of a gasket brings the problem ofshrinkage and break-up, which destroys the integrity of thegasket/mating surface.

Tackiness has been found beneficial since there is also vibration andflexing of the mating surfaces. Tackiness and resiliency provide abetter seal should there be a slight separation between the matingsurfaces.

SUMMARY OF THE INVENTION

Applicant's novel gasket consists of two parts. The first part comprisesa skeletal member—typically an open-weave mesh member and, moretypically, an open-woven mesh made of a metallic material or anon-metallic fabric such as fiberglass.

The second part of applicant's novel gasket is a flexible resilient bodymember typically formed around and through the skeletal member so thatthe skeletal member is substantially encapsulated within the resilientbody member and gives some structure and form to the gasket.

The gasket and gasket tape are usually tabular in shape and the skeletalmember and resilient body share a tabular shape and plane. However, whenviewed in cross-section, Applicants skeletal member is not centeredbetween the two opposed tabular surfaces of the gasket (or gasket tape),but instead is closer to one surface than the other. It is believed thatthis property provides selective retentivity to the material.

The resilient body is typically comprised of a semi-solid gelatinpolyurethane, typically between 40 and 150 (10⁻¹ mm) cone penetrationand having a surface tackiness of between about 2 to 7 inch pounds andwhich tackiness allows some adhesion to a metal mating surface, but willrelease easily and leave no residue upon release. The resilient bodywill not undergo dessication, does not leak oil, but retains memory anddoes not absorb more than about one percent by weight water. Otherresilient, pliable bodies may be used, such as silicon or polyolefinicblock copolymers or other materials with similar cone penetration andtackiness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1A illustrate prior art gaskets and their use.

FIG. 2 is a cross-sectional view of Applicants preformed gasket.

FIG. 3 is a side elevational view of Applicants preformed gasket in use.

FIGS. 4, 5 and 6 are elevational views of various “footprints” ofApplicants preformed gaskets.

FIG. 7 is a cross-sectional elevational view of Applicants gasket tape.

FIG. 8 is a perspective view of a step in the manufacture of Applicantspreformed gaskets.

FIG. 9 is a perspective view of another step in the process ofmanufacturing Applicants preformed gaskets.

FIG. 9A is a side elevational view of a table for use in the method ofmanufacturing Applicants gasket material and illustrating Applicants'gasket material on the upper surface thereof.

FIG. 10 is a perspective view of a manufacturing step in preparingApplicants' gasket material.

FIG. 11 is a perspective view of a step in the manufacturing ofApplicants' preformed gaskets.

FIG. 12 is a side elevational view of a step undertaken in preparationfor manufacturing Applicants gasket material.

FIG. 13 is a side elevational view of a table for use in the manufactureof Applicants gasket tape illustrating the stretching and clamping of awoven, non-metallic fiberglass member against the upper surface of thetable, the table upper surface having been covered with a release film.

FIG. 14 is a perspective view of the cutting of gasket tape stock intotape.

FIGS. 15, 15A and 15B illustrate a method of using Applicants preformedgasket with a liquid, curable mix with a preformed gasket to provide aneffective gasket seal between an aircraft skin and an aircraft antenna.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 1A illustrate a prior art gasket. In FIG. 1 the prior artgasket is seen to contain a woven, typically mesh member within a gelbody. However, the mesh member is located in a central area of thegasket body between the two other outer faces of the gasket, This is tobe compared to Applicant's preformed gasket 10 as illustrated in FIG. 2.Applicant's preformed gasket 10 has a metallic skeletal member 12 (ornon-metallic skeletal member 12A, see FIG. 14) wherein the skeletalmember lays close to or adjacent one of the two outer surfaces of thegasket. One beneficial result of this placement is that Applicant'sgasket has selective tackiness or retentivity, unlike prior art gaskets.Without such selective retentivity or tackiness, when prior art gasketsundergo tension during the release of the mating surfaces as illustratedin FIG. 1A (Prior Art) one face of the gasket often sticks to one matingsurface and the other face of the gasket to a second mating surface.Such a result may be damaging to the gasket, preventing its reusability.

As seen in FIG. 2, Applicant's preformed gasket or gasket tape (FIG. 7)includes a skeletal member which may be metallic 12 or nonmetallic 12A.A typically woven skeletal member is, more typically, a woven aluminummesh of thickness typically between 0.11 to 0.25 mil. Non-metallic mesh12A (see FIGS. 13 and 14) may be woven fiberglass, for example, as whenused in Applicant's gasket tape 16 typically between 7 and 20 mil.Sources of 1010 aluminum wire mesh are Estey wire and woven fiberglassis available from Teague Lumber as part number 337,600.

Substantially encapsulating skeletal member 12 or 12A is a resilientbody 14 typically a semisolid gel and more typically formed from acurable polyurethane mix. The resilient body includes a first surface14A and an opposed second surface 14B, the two surfaces with parallelplanes. A typical thickness of Applicant's preformed gasket 10 is 0.032inches to 0.050 inches before compression. A typical thickness ofApplicants gasket tape is between 0.032 and 0.060 inches beforecompression. The preformed gasket and tape share the same resilient bodyand both have a sticky or tacky surface typically in the range of 2 to 7inch pounds.

FIG. 3 illustrates Applicant's gasket as it is used to mount between twomating surfaces, here aircraft skin As and aircraft antenna Aa, withpreformed gasket 10 cut to dimensions dictated by the specifications ofthe antenna. It is placed between the aircraft skin and antenna andfasteners are tightened down typically to between about 15 and 35 inchpounds, to compress and slightly deform (squish out along the gasketedges) the gasket.

FIGS. 4, 5, and 6 illustrate three “footprints” available for Applicantspreformed gasket.

EXAMPLE 1

Applicant provides in example 1 a preformed gasket 10 with a footprintsimilar to FIG. 4 with an inner diameter about 5 inches and an outerdiameter of 7 inches. The gasket has a resilient body of about 40 milthickness comprised of polyurethane from a curable mix available fromKBS Chemical of Fort Worth, Tex. as part numbers P-1011 (polyol) andU-1010 (urethane). Aluminum mesh of about 22 mil thickness is used. Thepreformed gasket was installed on a commercial jet airliner (Boeing 737)between the aircraft skin and the aircraft antenna to between 15 and 35inch pounds pressure. The resulting compression allowed the wire mesh toground the antenna to the skin, with the making surfaces about 20 mildistance apart. Upon removal, after 7 months of service, there wasobserved clean separation of the antenna from the gasket and the gasketmaintained adhesion to the aircraft skin, expanding to about 40-90% ofits original thickness and shape. The gasket did not dry out, andmaintained its structural integrity and other chemical and physicalproperties, providing an effective seal.

EXAMPLE 2

A second gasket, similar in dimensions and structure to that set forthin Example 1, was joined between two mating surfaces under conditionssimilar to Example 1 and underwent 1,554 hours of salt fog testing perASTM B 117. This gasket had a central cutout area in which a high tac,self leveling, green polyurethane sealant (Part No. U-1020 and P-1021from KBS) was injected. The gasket was subject to a specified torque of15 and 35 inch pounds. Upon release of the two mating surfaces thegasket was seen to maintain its integrity and to release clean from onemating surface of the two mating surfaces. It was seen to retain itsresiliency and memory, as did the gasket in Example 1 above making aneffective environmental seal.

FIG. 7 illustrates the use of Applicant's unique gasket material in tapeform 16, rolled up and available to be cut to length for placing betweena pair of mating surfaces or as a self sealing tape. Applicant's tape 16uses, typically, the same polyurethane body as preformed gasket 10 whichhas surface tackiness and has a mesh, 12A, typically woven fiberglass,that is closer to one of the two tape other surfaces then to the other.This is believed to result in Applicants unique selective retentivity.

FIGS. 8, 9, 10 and 11 illustrate a method of producing Applicant'sprecut gasket 10.

The first step is the flattening step. The purpose of this step is toflatten out a skeletal member 12. The way in which this is done, if theskeletal member is metallic wire mesh, is to place the wire mesh 12between two flat weighed members 20A and 20B and then placing theweighed members with the wire mesh between them in an oven 22. The wiremesh is typically 18 inches by 24 inches and the weighed members aretypically ¼″ stainless steel plates. The mesh and weighed member aretypically laid flat in an oven 22 and heated 60 degrees F. for about 30minutes. This anneals the metallic wire mesh and keeps it flat. Themetal plates and the wire mesh are then removed from the oven andallowed to cool. Following cooling the weighed plates are removed andthe wire mesh is ready for placement onto flat table 24.

At this point it is germane to examine the nature of flat table 24 inmore detail. With reference to FIG. 9A, table 24 has legs and a tabletop. The table top typically includes a flat transparent glass member24A with a flat upper surface. It also includes beneath the glass member24A longitudinal aligned flourescent lights 24B. Before placement ofwire mesh 12 onto the glass table top a release sheet, such as an FEPsheet (fluorinated ethylene propylene) film is applied to the table top.The FEP film is inert and will not stick to the polyurethane mix or thecured mix and will allow a clean removal of the cured polyurethane mix,which comprises the resilient body, from the table top. It is noted withreference to FIG. 12 the FEP film is typically applied to the flat glasstable top 24A from a roll, after Windex® an ammonia based cleaner 38 isapplied to the surface of a table top and a squeegee 40 is used tosqueeze out any air bubbles. This is done to insure a flat, bubble freesurface for gasket formation. Thus, it is seen with reference to FIGS.9A and 12 that table top 24A has been prepared prior to the placement ofthe flattened wire mesh on top thereof, with an FEP or otherwisesuitable release film which will lay flat to the table top, be inert tothe cure mix and allow the gasket material to release therefrom.

The next step in the manufacture of the preformed gasket, may be calledthe “mixing and pouring” step and is best illustrated with reference toFIG. 9. In FIG. 9 it is seen that a mix applicator 28 containing acurable mix of resilient body such as a mix of polyol and urethaneavailable from KBS Chemical as set forth above, is applied to the meshthrough the applicator. The prior art applicator stores the liquid mixtypically as a resin (here urethane) and hardener (here polyol) in thebody thereof, but injection through the nozzle thereof allows the twocompositions to mix. Thus, in the process of pouring or applying theresilient body liquid mix, the two components are typically combined.This application and pouring step is typically done at room temperature.Moreover, it is noted that the resilient body liquid mix is selfleveling. This step may also be done as two separate steps. First, onecould separately mix the two components of the curable mix and, beforeit begins to set, apply it by pouring or any other suitable manner, ontothe skeletal member.

With a minimum practice and experience the proper amount of liquid mixfor the mesh may be determined. That is, sufficient liquid mix should beapplied to the mesh for it to sufficiently cover the mesh such that theresilient body contains the wire mesh closer one surface than the other(see FIG. 2). For example, it been determined that using a 10½ inch by17 inch 22 mil aluminum wire mesh such as set forth above, one appliesabout 160 milliliters of mix, typically, in the crisscross or zig zagpattern as illustrated in FIG. 9. This will typically result in a gasketof about 40 mil thickness.

The next step in preparing Applicant's preformed gasket is to allow theliquid mix to cure. Typical time to curing is about 4 hours at roomtemperature. Upon curing a second FEP layer here 30A (see FIG. 10) isapplied to the top surface of the gasket stock 10A as seen in FIG. 10.This second layer of FEP material will help protect the gasket stock inhandling and also will release easily from the surface therefrom.

Further in FIG. 11 it is seen that gasket stock 10A may be cut with adie stamp machine 34 in ways known in the trade to form precut gaskets10 to any number of suitable configurations (see for example FIGS. 4, 5and 6).

FIG. 13 illustrates a manner for making Applicant's gasket tape 16. Thisinvolves the step utilizing a table such as is illustrated in FIG. 9Aand stretching a non-metallic skeletal member 12A from a roll or otherstock of such material under tension atop the FEP layered table. Sometension and clamping is necessary to insure that the mesh 1 2A ismaintained flat against the FEP bottom layer 30B.

The mixing and pouring step is similar to that illustrated in FIG. 9,with the same resilient body liquid mix as used in the preformed gasket10, coating all of the skeletal member to a thickness sufficient toplace the skeletal member closer to one surface of the gasket tape thanthe other.

Following a period of curing the resulting gasket tape stock asillustrated in FIG. 14 may be cut longitudinally, covered with a toplayer of FEP and rolled into a roll resulting in the gasket tape 16illustrated in FIG. 7.

This tape may be then used in lining aluminum structural members of theframe of aircraft such as those in cargo bays and also on aluminummating surface beneath lavatories and galleys, where moisture may be aproblem. This will help prevent access of moisture to the structuralmember. It is noted that use of Applicant's tape or gaskets will be selfsealing around fasteners hole. This occurs when there is some defamationof the tape or gaskets at their edges under compression between the twojoined mating surfaces.

In summary, it may be seen that Applicant's unique method ofmanufacturing either the tape or the prevent gasket includes the step offlattening the skeletal member against a flat surface, typically a tabletop and more typically table top against which a flat release film suchas an FEP film has been placed thereon. It is seen that a curable liquidmix is combined and applied in liquid form, to cover the skeletal memberto a depth sufficient to insure that the skeletal member is closer tothe bottom surface of the resulting stock then to the upper surface. Itis further seen that the resilient body liquid mix is typically selfleveling and will cure at room temperature. The resulting stock may bethen precut to a desire shape or cut to a preselected width and rolledup in a form of gasket tape. It is further seen that the gasket tape, asillustrated in FIG. 7 is provided with a first protected film 18A and asecond protective film 18B, typically FEP and that after by cutting, theprecut gaskets are typically covered top and bottom with the sameprotective FEP film.

FIG. 15 shows Applicants preformed gasket 10 ready for installationbetween two mating surfaces As and Aa. FIG. 15A illustrates the use ofnon-preformed pliable sealant mix 13, typically a resin and a hardner,more typically a polyurethane curable mix. Mix 13 will set in place, andmay fill any central cut-out areas 13A in gasket 10. This will oftenprotect against the trapping of moisture in such area. Note that thiscurable mix should have the beneficial properties of the resilient bodyof Applicants preformed gasket 10. Such curable mixes are available fromKBS Chemical of Fort Worth as U-1020 and P-1021.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitedsense. Various modifications of the disclosed embodiments, as well asalternative embodiments of the inventions will become apparent topersons skilled in the art upon the reference to the description of theinvention. It is, therefore, contemplated that the appended claims willcover such modifications that fall within the scope of the invention.

We claim:
 1. A gasket material for sealing between two members, thegasket material comprising: a flexible skeletal member; and a flexible,compressible, resilient body member having a tacky outer surface, theresilient body member for substantially enclosing the skeletal member,the resilient body member having a top surface and a bottom surfacewherein the flexible skeletal member is closer to one of the top surfaceor the bottom surface than the other wherein the flexible skeletalmember is substantially encapusalated in the resilient body member andwherein the top surface of the gasket material has a first tackiness andthe bottom surface of the gasket material has a second tackiness, thefirst tackiness being greater than the second tackiness.
 2. The gasketmaterial of claim 1 wherein the resilient body member is comprised ofpolyurethane.
 3. The gasket material of claim 1 wherein the flexibleskeletal member is comprised of a metallic material.
 4. The gasketmaterial of claim 1 wherein the flexible skeletal member is comprised ofa non-metallic material.
 5. The gasket material of claim 3 wherein theflexible skeletal member is woven aluminum mesh.
 6. The gasket materialof claim 4 wherein the flexible skeletal member is woven fiberglassmesh.
 7. The gasket material of claim 1 wherein the resilient bodymember is substantially polyurethane and the skeletal member is a wovenmetallic material.
 8. The gasket material of claim 1 wherein theskeletal member is between 7 and 25 mil. thick and the resilient bodymember is up to 45 mil. thick.
 9. The gasket material of claim 1 whereinthe resilient body member has a cone penetration of 40 to 150 (10⁻¹mm).10. The gasket material of claim 1 wherein one other surface has a peelstrength of about 5 inch pounds and the other has a peel strength ofabout 3 inch pounds.
 11. A method of making a gasket material, themethod comprising the steps of (a) providing a flexible skeletal member;(b) providing a curable mix of a resilient composition; (c) laying theflexible skeletal member on a flat, horizontal support surface; (d)pouring the curable mix onto the skeletal member so as to substantiallyencapsulate the skeletal member; (e) allowing the curable mix to cure;(f) cutting the cured piece to a predetermined gasket profile.
 12. Themethod of claim 11 above wherein, before step (c), undertaking the stepof providing the flat, horizontal support surface with a release film.13. The method of claim 11 above wherein the providing step (b) includesproviding a curable polyurethane mix.
 14. The method of claim 13 abovewherein the curable mix is one part resin and one part hardener and thepouring step includes a step of combining the resin and the hardener.15. The method of claim 13 above wherein, before step (c) is a step offlattening the flexible skeletal member.
 16. The method of claim 15above wherein the flattening step includes heating the skeletal memberwith the skeletal member under pressure and the providing step includesproviding a metallic skeletal member.
 17. The method of claim 11 abovewherein the laying step includes stretching and clamping the skeletalmember to the support surface and the providing step includes providinga non-metallic skeletal member.
 18. A gasket material for sealingbetween two members, the gasket material comprising: a flexible skeletalmember; and a flexible, compressible, resilient body member having atacky outer surface, the resilient body member for substantiallyenclosing the skeletal member, the resilient body member having a topsurface and a bottom surface wherein the flexible skeletal member iscloser to one of the top surface or the bottom surface than the otherwherein the flexible skeletal member is woven fiber glass mesh.
 19. Agasket material for sealing between two members, the gasket materialcomprising: a flexible skeletal member; and a flexible, compressible,resilient body member having a tacky outer surface, the resilient bodymember for substantially enclosing the skeletal member, the resilientbody member having a top surface and a bottom surface wherein theflexible skeletal member is closer to one of the top surface or thebottom surface than the other wherein the skeletal member is between 7and 25 mil. thick and the resilient body member is up to 45 mil. thick.20. A gasket material of claim 19 wherein the resilient body member iscomprised of polyurethane.
 21. The gasket material of claim 19 whereinthe flexible skeletal member is comprised of a metallic material. 22.The gasket material of claim 19 wherein the flexible skeletal member iscomprised of a non-metallic material.
 23. The gasket material of claim19 wherein the flexible skeletal member is substantially encapsulated inthe resilient body member and wherein the top surface of the gasketmaterial has a first tackiness and the bottom surface of the gasketmaterial has a second tackiness, the first tackiness being greater thanthe second tackiness.
 24. A gasket material for sealing between twomembers, the gasket material comprising: a flexible skeletal member; anda flexible, compressible, resilient body member having a tacky outersurface, the resilient body member for substantially enclosing theskeletal member, the resilient body member having a top surface and abottom surface wherein the flexible skeletal member is closer to one ofthe top surface or the bottom surface than the other; wherein one of thetop surface or the bottom surface has a peel strength of about 5 in.pounds. and the other of the top or the bottom surface has a peelstrength of about 3 in. pounds.